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Water Chestnut

Photo by Leslie J. Mehrhoff, University of Connecticut, Bugwood.org

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Common Name: Water chestnut
Scientific Name: Trapa natans
Origin: Europe and Asia


Water chestnut is a fast-growing, floating annual that can grow to 16 ft. It has feathery, submersed leaves and triangular, toothed, floating leaves that are glossy. Floating leaf stalks have visible bulbous bladders and commonly form rosettes. Flowers with four white petals normally bloom in July. The most distinctive trait of this plant is its thorny nutlets which mature in late summer. Reproduction occurs from these very sharp nutlets and from fragmentation of the rosettes.


Water chestnut is found in slow-moving and/or still, high-nutrient waters with soft substrate and neutral to alkaline pH.


Impenetrable mats of water chestnut can cover large expanses of water, altering water quality and clarity, eliminating the growth of native aquatic plants, and making boating, fishing and swimming hazardous.


Small populations can be controlled by hand pulling. Large infestations have been controlled in the northeast by the use of mechanical harvesters and the application of aquatic herbicides. Bio-controls are currently being researched.